Modern vehicles have bumper systems tuned for particular energy absorption profile during a vehicle-to-vehicle impact and/or vehicle-to-barrier impact. However, tuning of bumper systems can be challenging due to conflicting design requirements, such as limitations on the packaging space occupied by the bumper system (i.e., energy absorber and/or bumper beam), limitations on bumper beam flexure and rear intrusion into the space behind the bumper beam, and limitations on cost, quality, dimensional consistency and consistency/predictability of the impact energy-absorbing profile during the impact stroke itself.
Additionally, in Europe and the Pacific region, the Economic Commission for Europe (ECE) 42 (1 Jun. 1980) and Research Council for Automobile Repair (i.e., low speed 15 kilometers per hour (kph)), Offset Insurance Crash Test to determine damageability and repairability features of a Motor Vehicle, January 1999 (hereinafter “RCAR”) require that bumper systems at both the front and rear side of the vehicle withstand impact as specified in these standards. In the U.S., a vehicle has to meet Federal Motor Vehicle Safety Standards (FMVSS, i.e. Title 49 of the Code of Federal Regulation (CFR) part 581; hereinafter “FMVSS part 581”) and RCAR, and the Insurance Institute for Highway Safety 10 kph low speed frontal and rear test, May 2006 (hereinafter “IIHS 10 kph test”). Economic Commission for Europe (ECE) regulation No. 42 is similar to FMVSS part 581, but slightly less stringent, specifying performance requirements for passenger cars in low-speed front and rear collisions.
FMVSS part 581 applies to front and rear bumpers on passenger cars to prevent the damage to the car body and safety related equipment. It requires that a car's expensive parts such as tailgate, fog lamp, back panel, etc., continue to operate normally after the car has been impacted by a pendulum or moving barrier on the front or rear longitudinally at 4 kilometers per hour (kph; about 2.5 miles per hour (mph)) and on the front and rear corner at 2.5 kph (˜1.5 mph) at varying heights (15 inches (381 millimeters (mm) to 21 inches (533 mm))) from the ground. Economic Commission for Europe (ECE) regulation No. 42 is less stringent as the reference height of the pendulum impactors from the ground is fixed as 455 mm (about 18 inches) from the ground front.
There is a continuing need for lighter weight energy absorbers that meet governmental standards and original equipment manufacturers (OEM) space limitations.